fix(plugin-state): track vision-capable multimodal models

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/plugin-state.ts

@@ -1,11 +1,18 @@
+export type VisionCapableModel = {
+  providerID: string
+  modelID: string
+}
+
 export interface ModelCacheState {
   modelContextLimitsCache: Map<string, number>;
+  visionCapableModelsCache?: Map<string, VisionCapableModel>;
   anthropicContext1MEnabled: boolean;
 }
 
 export function createModelCacheState(): ModelCacheState {
   return {
     modelContextLimitsCache: new Map<string, number>(),
+    visionCapableModelsCache: new Map<string, VisionCapableModel>(),
     anthropicContext1MEnabled: false,
   };
 }